A solution of H2SO4(aq)H2SO4(aq) with a molal concentration of 2.55 m2.55 m has a density of 1.151 g/mL.1.151 g/mL. What is the molar concentration of this solution?

Molar concentration = 2.35 M (Approx)

Explanation:

Given:

Density of solution = 1.151 g/ml

2.55 molal = 2.55 moles of solute/ kg

Find:

Molar concentration

Computation:

Molar mass of H2SO4 = 2(1.0079) + (32.066) + 4(15.999)

Molar mass of H2SO4 =  98.0778

Molar mass of H2SO4 = 98 g/mol (Approx)

Mass of solution = 2.55(98)g + 1000 g

Mass of solution = 1249.9 gm

Volume of solution = 1249.9 / 1.151 = 1086 ml

Volume of solution = 1.086 L

Molar concentration= 2.55 / 1.086

Molar concentration = 2.35 M (Approx)

[H₂SO₄] = 2.35M

Explanation:

Our solute is the sulfuric acid → H₂SO₄

To determine the molar concentration we need the volume of solution.

Mass of solute: moles . molar mass

2.55 mol . 98 g/ 1 mol = 249.9 grams

Mass of solvent: 1 kg (we know this, because data refers about molality, moles of solute in 1kg of solvent)

Mass of solution = solute + solvent → 1000 g + 249.9 g = 1249.9 g

We apply density: Density = Mass / volume

1.151 g/mL = 1249.9 g / mL

mL = 1249.9 g/ 1.151 g/mL = 1086 mL

Molarity → mol/L → 2.55 moles/1.086L = 2.35 M

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.